badboy, was the scarf worked long-wise or short-wise? That is, is each row short (across the scarf, which I'm assuming is rectangular) or long (the length of the rectangle)?
I'm a punk crocheter often bequeathed others' mistakes. Sometimes I frog the whole thing out to reclaim the yarn. Mostly I wing a solution as jazz.
My idea is related to your "sewed edges" one, where your instinct is to overwork the loopy zone.
If the nasty stitches are along the short side of the scarf, consider reinforcing them and then overstitching the edge using a lightweight bulky yarn in a pattern/stitch you like.
So, for instance, you can weave a length of something like Caron One Pound (herky washable uber string) or other appropriate yarn in a similar color in and out of those stitches. That becomes your base to cover up with good snug stitches, enclosing the loopy ones.
I like reinforcing edges with slip stitch or single crochet, then working prettier things into that. Sometimes when I need to cover up an edge I don't like, I reinforce it than work a simple hyperbolic curved border into it. You do that by setting down a row of say single crochet, nicely tensioned, then working an increasing number of stitches into each stitch in the previous row. So for instance, if you put two crochet stitches into each previous row's stitches, and continue doing that for three or four rows, you'll quickly make a spectacular fluted edge.
You can also use the loopy edges to advantage. Since they aren't properly filled tension-wise with the next row of stitches, then maybe you can fill them with something. Can you crochet a contrasting chain, then work it in an organized way into the loops? Can you catch up several loops and use them as part of other stitches you apply?
I am really a punk looper, though. If you look online at various "freeform" crochet sites, you will see that there are no rules. You can even take what you have of the scarf, and overwork it however you feel like. Ask it what it wants to be when it grows up. A scarf doesn't have to be a scarf. Try folding it different ways and seeing if it wants to be something else, like a basket or a hat or a coffeepot cozy. Sometimes a piece of crochet is just like a person: it may have faults, but fixing them is less fun than living with them creatively.